A machine tool such as an automatic lathe including a workpiece supply device that supplies a workpiece to a machining area for a workpiece (machining material) has been known (see Patent Literature 1, for example). In the workpiece supply device (loader) of Patent Literature 1, a loader head holds the workpiece supplied outside the machining area, and the loader head enters the machining area through an opening part provided in a body cover that covers the machining area to transfer the workpiece to a main spindle of the machine tool. A movement mechanism of the loader head is provided with a shielding plate capable of closing the opening part. The shielding plate closes the opening part while the loader head locates in the machining area. The closing of the opening part by the shielding plate prevents moisture and mist of cutting fluid filled in the machining area from scattering outside the machining area through the opening part.
When the loader head moves outside the machining area after the transferring of the workpiece is completed, the shielding plate separates from the opening part to open the opening part. The body cover is provided with a shutter, which closes the opening part in an openable and closeable manner, separately from the shielding plate. By closing the opening part with the shutter after the workpiece is supplied by the loader, for example, the cutting fluid and the moisture are prevented from scattering outside the machining area through the opening part during the machining of the workpiece.